Temperature sensors are devices used to detect the temperature of a device that contains the sensor or is physically located near to the sensor. In this way, the operation of a circuit may be controlled as a function of its temperature. Such control may be advantageous in the case of applications that require heat dissipating devices, and for other purposes. For instance, it may be necessary to incorporate a heat sink in an integrated circuit, or to force air over the integrated circuit if the integrated circuit has the potential of ever exceeding the passive cooling ability of the integrated circuit. With a temperature sensor, it may be possible to avoid these instances and, thus, to avoid the requirement of a heat sink, fan, etc. altogether.
Known thermal sensors have traditionally relied on complex discrete solutions. For instance, known thermal sensors incorporate resistors, capacitors, operational amplifiers, and ring oscillators to detect changes in temperature. Unfortunately, these devices may be incompatible with modern, complementary metal oxides semiconductor (CMOS) manufacturing processes. And, these solutions may require complex control circuitry to operate.
Other known solutions are not fully integrated. A fully integrated solution is one in which the sensing element resides on the same integrated circuit whose temperature is of interest. Instead, prior solutions have located a sensing element near to the device of interest. This solution is more expensive and less responsive to temperature changes. These non-integrated solutions are less responsive to temperature changes due to the thermal resistance between the external sensor and the device of interest.